We propose to maintain and expand the population-based, computerized San Francisco Mammography Registry (SFMR) so that it can continue to serve as a resource for conducting high quality, clinically significant research related to breast health and breast cancer. Specifically, we will continue to collect demographic, clinical, and risk factor information, as well as mammography interpretations, cancer outcomes obtained through linkage with the regional population-based Northern California Surveillance, Epidemiology, and End Results (SEER) Program, and cause of death through linkage with the California Department of Health Services Vital Records. The diverse cohort of over 265,000 women that participate in the SFMR includes 47 percent non-Hispanic whites, 33 percent Asian/Pacific Islanders, 5 percent Hispanics, and 8 percent African Americans. Since the registry's inception, information on over 800,000 mammography examinations and 13,000 breast cancers has been collected from 20 facilities in San Francisco and Marin Counties and sent to the Breast Cancer Surveillance Consortium (BCSC) Statistical Coordinating Center. Annually, information is collected on about 111,000 mammography examinations and 1,000 cancers. SFMR data collection provides investigators the opportunity to use robust data, and access to a well characterized population to conduct research. Potential uses of the registry include studies to evaluate: 1) the performance of mammography according to the characteristics of women, radiologist's experience and practice, and tumor biology, 2) associations between risk factors and types of breast cancer, 3) associations between risk factors and breast density, and the biology of breast density, 4) secular trends in breast cancer risk factors, health habits and mammography, 5) quality of breast health care, 6) new markers of risk and rapidly testing their predictive value for breast cancer, and 7) emergent breast imaging technologies. In addition, access to women in the SFMR allows for development of cohorts, enrollment in randomized controlled trials, and conduction of cross-sectional and case-controls studies to examine breast health and health services related issues. The SFMR database provides a valuable resource and rich platform for students, fellows, junior faculty members and other investigators interested in conducting research in the areas of breast imaging, breast health and breast cancer. SFMR investigators will facilitate use of the SFMR and BCSC locally and nationally through several postgraduate training programs at UCSF, presentations at national meetings, and presentations and interactions with members of the Breast Oncology Program at the UCSF Cancer Center.